Google webmaster tools is showing ranking of my keyword 2.2 but serp is not displaying in 120 top results and when i do organic search of keyword i didnt find in even first 150 results. what should i do

Just for your information, Google Webmasters or Search Console always show average position of a keyword.

Secondly, this ranking depends upon the time zone you have selected that means if you have selected US time zone then your rankings shown in Search Console will be the keywords ranking in US. Hence, if your target location is India, something else it's wise to select the targeted location.

The short version, if you want to skip me ranting like a lunatic: Google Search Console query data is, as far as I can tell, completely, 100% useless. It’s not a good ‘relative comparison.’ It’s so wrong that it might actually be a bad idea to use it at all.